PROJECT SUMMARY There are around 1200 emergency room admissions annually in the US due to scuba injuries. From those, around 500 relate to Decompression Sickness (DCS), a condition developed when nitrogen dissolved in blood and tissues at high pressure forms bubbles as pressure decreases. Treatment for DCS is recompression in hyperbaric chambers, following slow and controlled normalization of pressure conditions. Early intervention is crucial once the onset of DCS symptoms are detected, however, it is limited to management of symptoms while quick evacuation to specialized medical facilities is arranged. SIL Technologies is proposing to open a new avenue for early treatment that will be initiated in the field by emergency responders. The treatment will use innovative technology able to disturb the bubbles in the bloodstream splitting them into smaller ones that will dissolve expeditiously. Thanks to the proposed technology, it would be possible to prevent the worst damages created by DCS which are related to the presence of the largest bubbles. Moreover, the recovery of the patient will be drastically accelerated. The long-term objective of the research is to normalize the presence of bubbles after 15 minutes of treatment without further secondary effects. The specific aims of this research effort are i) to demonstrate the capability of the technology to disturb bubbles in the blood stream dividing them into smaller ones, ii) to determine the operating requirements of the intended medical device, iii) to demonstrate hematologic integrity after treatment, and iv) to estimate the duration of the treatment required for complete dissolution of N2 depending on the severity of the initial conditions. The technology herein proposed evolves from years of basic research conducted to detect bubbles in bloodstream and tissues. It consists of a piezoelectric transducer shaped like a ring, or an array of transducers that will be placed belting the patient thigh. Piezoelectrics will be set to operate at its resonance frequency, therefore, creating a standing acoustic wave inside the thigh. The bubbles will be fragmented into smaller ones at sufficiently high amplitude of the resonant wave. The gas will then dissolve quickly, since the gas-liquid surface interface is multiplied. This research combines experimental and numerical efforts in a test section consisting of fresh swine thighs where iliac and femoral vessels will be dissected and isolated. A stabilized blood circuit will be prepared using plastic infusion cords with arteries as inflow side and veins as outflow. Bubbles of controlled size and in a controlled number will be inserted in the blood stream and samples will be collected for analysis after passing along the tight, where the piezoelectric transducers will be placed and set to operate. Experiments will be conducted within five hours after death of the swine. The size and amount of bubbles crossing the piezoelectric will be determined following well established methods relying on terminal velocity form buoyant effects. Hematological integrity will be monitored using a chemistry analyzer paying special attention to the following parameters: WBC, LYMPH, MONO, GRAN, HCT, MCV, RDW, HGB, MCHC, MCH, RBC, PLT, MPV and PLT size distribution histograms. Depending on the analytical results, microscopy studies may be conducted to determine the existence of blood clots.